The quality of barley for the range of end uses from animal feed to brewing is determined by many genes, making the breeding of new barley varieties difficult. Understanding of the molecular basis of barley quality has been advanced by biochemical studies. More recently, molecular genetic tools are allowing the analysis of the biochemical factors contributing to grain quality. Many genetic loci influencing key quality attributes have been identified by gene mapping. Limited success has been reported in using this information to select for quantitative trait loci for these quality traits in plant breeding. Genomic techniques allowing more detailed analysis of variations in the barley genome in relation to quality promise to extend significantly the value of molecular genetic approaches to barley quality improvement. Definition of the genetic basis of malting quality requires the identification of the genes involved in germination and endosperm modification. Feed quality remains difficult to define. Recent advances are likely to accelerate the rate of discovery, providing new options for analysis of barley quality.

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Molecular basis of barley quality

A novel process for microencapsulation of fish oil with barley protein

By providing both spatial and temporal information remote sensing may function as an important source of data for site-specific crop management. This technology has been used for nitrogen application strategies to obtain optimum yield and grain quality. Here, the objective was to use early repeated remotely sensed multi-spectral data to predict grain yield and quality for winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). The crops were sown with two different seeding rates and a wide range of nitrogen strategies were applied. Multi-way partial least squares regression (N-PLS) was used to predict grain yield and protein content. The results were compared with unfold-PLS1 and PLS1 using reflectance data from the last measurement day. Both single reflectance wavelengths and selected vegetation indices were used simultaneously. The results reveal that all models can make a good prediction of yield in both crops with unfold-PLS1 and N-PLS as the best. However, estimation of grain protein content at harvest was very poorly determined in barley, as no relation between the reflectance measurements and barley protein content was obtained. The relation between reflectance measurements and protein content was slightly better in wheat, where especially N-PLS improved the prediction of grain protein content. The overall conclusion of the present experiments is that data from repeated measurements of reflectance used in multi-way partial least squares regression before heading improved the prediction of grain yield and protein content in wheat and barley.

Predicting grain yield and protein content in winter wheat and spring barley using repeated canopy reflectance measurements and partial least squares regression

Antioxidative properties of partially purified barley hordein, rice bran protein fractions and their hydrolysates.

Protein and hordein content in barley seeds as affected by nitrogen level and their relationship to beta-amylase activity

Improvements in malting quality are important if barley from south-eastern Australia is to remain competitive on export markets. Grain is desired that will produce high levels of malt extract and diastatic power but has moderate levels of grain protein. To examine cultivar and environmental effects, especially nitrogen (N) fertilizer, on levels of malting quality parameters and their correlations, seven cultivars of barley were grown in a fallow and pea stubble rotation with five levels of N fertilizer in the Wimmera region of Victoria in 1990 and 1991. The first season was relatively dry and warm, while the second was wetter and cooler. Grain yield and malt extract were markedly lower in 1990 than 1991, and grain protein concentration, grain screenings and diastatic power were significantly higher. Grain protein and diastatic power increased almost linearly with increasing N application, with a higher rate of increase in 1990 than in 1991. Malt extract declined almost linearly with increasing N application, but the change in rate of decline between seasons was less than the change of rate of increase of grain protein. Environmental correlations between protein concentration and malt extract, and between malt extract and diastatic power, were negative. They were close to -1.0 when the environmental factor varying was restricted to N fertilizer, but were of a smaller absolute magnitude when seasons and rotations were also allowed to vary. In contrast, genotypic correlations were of intermediate magnitude. Broad-sense heritabilities for malt extract and diastatic power were relatively high, even with such contrasting seasons. This indicates that it should be possible to develop cultivars for south-eastern Australia which have high malt extract and high diastatic power at low protein levels. However, applications of N fertilizer that raise grain protein concentration will reduce malt extract, with the effect much greater in drier, warmer seasons.

Cultivar and environmental effects on malting quality in barley

Grain from sowing time experiments at 1 site in 1984 and 2 sites in 1986 and 1987 in northwestern Victoria were tested for several grain and flour characters. The tests included grain protein percentage, sodium dodecyl sulfate (SDS) sedimentation volume, particle size index, milling yield, test weight and Pelshenke wholemeal fermentation time, although not all tests were carried out in all years at both sites. The findings are reported without analysis of the underlying processes involved. The effect of sowing time on grain protein percentage was variable; at Dooen in 1984 there was a slight decrease, at Dooen and Walpeup in 1986 there was an increase but there was no change at Dooen in 1987, as sowing time was delayed. Sowing time had a significant effect on SDS at Dooen in 1984 and Dooen and Walpeup in 1986. There were no marked trends at Dooen in 1984, but significant differences between individual sowing times, and in 1986 there was an inconsistent increase as sowing time was delayed. At Walpeup in 1986 there was a substantial increase in values as sowing time was delayed. Partial correlation coefficients, however, indicated that at Dooen in both years and Walpeup in 1986, variation for SDS was due almost entirely to differences in grain protein percentage, although at Walpeup in 1986 there was a slight additional effect of sowing time. Particle size index was significantly affected by sowing time at both sites in 1986; at Dooen there was a decrease as sowing time was delayed and then an increase for the last sowing time, and at Walpeup there was an increase as sowing time was delayed. Although some effects of sowing time on milling yield and test weight were statistically significant, only one had commercial significance-milling yield at Walpeup in 1986. Pelshenke time was affected by sowing time at Dooen in 1984 and Walpeup in 1986, but there were no obvious trends. Sowing time x cultivar interactions have implications for quality testing of wheat crossbreds. Grain growers can be reassured that sowing crops over an extended period appears to have little or no detrimental effect on grain quality with respect to bread baking properties. In some seasons, however, there may be substantial increases in grain protein percentage in later sown crops, although this would generally be associated with lower yields.

PJ Martin

Papers

Cultivar and environmental effects on malting quality in barley

Influence of sowing time on grain quality characters of wheat grown in north-western Victoria